Cartridge case



May 30, 1944. J. J. LAMBEEK 2,349,970

CARTRIDGE CASE Filed June 12, 40

Patented May 30, 1944 2,349,970 cam-amen CASE Adriaan Jan Jurriaan Lambeelr, Dordrecht, Netherlands: vested in the Alien Property Custodian Application June 12, 1940, Serial No. 340,193 In the Netherlands May 26, 1939 2 Claims. (Cl. 102-43) My invention relates to cartridge cases which are provided at their bottom with a central aperture for receiving a primer.

Such cases, which are used, for example, for cartridges having a diameter greater than about 2 cms., aresubjected during the firing to pressures exceeding about 2,000 kgs. per sq. cm. Althoughthe case fits snugly into the bore of the gun, it must be capable of resisting the deformation forces exerted on it during the firing and also must be so resilient that it does not become jammed in the bore due to permanent deformation.

It has been the general practice to form such cases by subjecting a brass plate to a series of drawing operations to thereby form a cupshaped body having a fiat or slightly-curved bottom, and then pressing the end to produce an internal boss and an outer rib. The bottom portion was then provided with a central threaded hole to receive the primer. In cases made in this manner the flow-lines of the metal have one of their ends at the surface of the central hole and extend substantially parallel to the outer surface of the bottom of the case toward the side surface of the case.

The main object of my invention is to improve the mechanical properties of such cases.

A still further object is to provide a case which can be readily and inexpensively reconditioned.

Further objects and advantages of my invention will appear as the description progresses.

In accordance with the invention I so form the case that the flow-lines of the metal, as taken in a section through the longitudinal axis of the case, have one end at the outer surface of the bottom of the case and extend through the bottom portion and then through the side portion with their other ends lying in this latter portion.

When the cartridge case of my invention has the same shape as the cases at present used, i. e. has an internal boss surrounding the central hole in the bottom, I prefer to so form the case that the flow-lines of the metal in the bottom portion when taken in a plane through the longitudinal axis of the case, have an- S shape. More particularly, these lines have one end at the outer surface of the bottom portion, curve down into the part of the boss adjoining the hole, then curve in the other direction through the outer portion of the bottom between the boss and the peripheral surface of the case, and have their other ends in the side wall of the case.

vention by a pressing or extrusion process at a low temperature in which a pre-shaped case having a flat bottom provided with a central hole is pressed to form the boss on the inner surface of the bottom. The pre-shaped case may be extruded from a thin circular plate. The material used for the case depends upon the conditions under which it will be used, but I have found that in most instances very satisfactory results are obtained not only with brass, zinc or the like, but also with light metals such as aluminium and alloys thereof.

In order that my invention may be clearly unterstood and readily carried into effect, I shall describe the same in more detail by comparison with the prior art and with reference to the accompanying drawing in which:

Figure 1 is a longitudinal cross section view of a portion of a cartridge case according to the prior art.

Fig. 2 is a longitudinal cross section view of a portion of a cartridge case according to my invention,

Fig. 3 is a longitudinal cross section view of a portion of a cartridge case according to another embodiment of my invention,

Fig. 4 is a longitudinal cross section view of a slug for making a cartridge case, and

Fig. 5 is a longitudinal cross section view of a pressing device for producing the bottom-piece of the cartridge cases according to the invention. I

The prior art cartridge case illustrated in Fig. I has a slightly tapering side-wall portion i of substantially cylindrical shape, and a bottom portion 2 provided with a boss 6. The portion 2 is provided at its center with a bore 3 having internal screw threads 4 for the attachment of a primer or percussion cap not shown).

The flow-lines of the metal at the section shown are made visible in known manner by etching the polished surface for example with nitric acid, hydrochloric acid or hydrofiuric acid. As shown, the flow-lines of the metal have one end at the surface of bore 3, extend through portion 2 substantially parallel to the outer surface thereof, and then down through the side-wall I. More specifically, line 20 starts at point 2! on the surface of bore 3 and at a point 22 merges with the remaining flow-lines to extend through the side-wall I.

The cartridge case shown in Fig. 1 was made, for example, by drawing a sheet of brass into a cup-shaped body and then pressing the bottom I prefer to form the case according to the inof this body to form the boss 0 and a rib 5.

cartridge case of the structure shown in Fig- 1 has the disadvantage that after it has mused, the reconditioning of the same is comited and expensive. More particularly, when .g reconditioned it is necessary to press the a into its correct shape and when this is done threads 8 are pressed out of shape and it is :ssary tore-tap the hol 8. As will be exned in more detail hereinafter this difilculty at present with the cases of the present invenbecause when reshaping such cases the wthreads 4 automatically assumetheir cor- I shape and re-tapping is unnecessary. lgures 2 and 3 illustrate cartridge cases acling to the invention and in these figures the .e parts are indicated by the reference nuals used in Figure 1. The case shown in ire 2 has a shape which is similar to that Figure 1 except that the bottom portion 2 substantially parallel surfaces. As shown flow lines of the metal have one of their ends he outer surface of portion 2 and extend out- 'dly through this portion with their other s in the side wall I. More specifically,the 28 has one end at point 24 on the bottom sur- 3 of the case and merges with the other flow as at a point 25. After a cartridge having h case has been fired, the case can be pressed k into its correct shape and the threads 4 vbe used without re-tapping. he case shown in Fig. 3 has the same shape the prior art case illustrated in Fig. l and has advantages described in connection with 2. In Fig. 3 the flow lines of the metal in section shown have an 8 shape. More parilarly, a flow line 28 has one end at point 21, urved portion 80 in the boss 6 and a second ved portion 28 in an outer part of the bottom 'tion 2 and merges at point 31 with the other v lines. The case shown in this figure can be onditioned merely by pressing the same into correct shape and without re-tapping the e 8. ['he method of making the case shown in Fig. 3 i be explained with reference to Figs. 4 and 5. e starting material is a slug 1 (see Fig. 4) ivided with a central aperture 8 which slug vy be of brass, zinc and the like, of a lighter tal such as aluminum, alloys thereof. This g may be cut from a drawn metal tube. This g is extruded by means of a suitable extrudin ,chine (not shown) into a cup-shaped body 8 c Fig. The aperture 8 in the slug serves centre the slug in the extruding machine. the cup-shaped body 9 is then given the shape the case shown in Fig. 3 by means of the mould awn in Fig. 5. This mould comprises a matrix supported in a stationary block l5, an upper 2 l8 having a projection and mounted, on a Inger H adapted to move in the direction of a arrow, and an ejectqrJS supported by a stationary cylindrical member l8. The ejector l3 has a circular rib i! on its upper surface for the purpose of forming the boss 8 (see Fig. 3).

In operating the device the cup-shaped body 9 provided with the central aperture 8 is arranged in the mould, with its side wall l8 inteiposed between the peripheral surface of ejector l3 and the inner surface of matrix II, the inner surface 1 of the bottom. of the cup-shaped body 9 engaging the top surface oi ejector II. The upper die In is then lowered in the direction of the arrow to press the bottom of the cup-shaped body into the desired form. Thus the edge 5 of the case (see Fig. 3) is formed in the recess IS-and the boss 8 which surrounds the aperture 8 in the bottom of the case is formed in the space within the circular rib I'I. When the case has been formed the upper die I8 is raised to such extent as to permit ejector l8 to force the finished case from the top of the matrix. During the formation of the raised edge 5 the material in the bottom portion will be compressed so that the hole 8 will be reduced in size. The shape which the hole 8 assumes during the extrusion is indicated by dotted lines 8| in Fig. 3. The excess material can be removed. for instance by boring or drilling or reaming, to form the hole 3 which is then tapped.

The reconditioning operation of a case may be performed in a press which is practically identical with that shown in Fig. 5. Eventually the surface may be somewhat convex, whereas the circular rib ll may be somewhat deeper.

Although I have described my invention with reference to specific examples and applications I do not desire to be limited thereto because obvious modifications will present themselves to one skilled in this art.

WhatI claim is:

1. A cartridge case comprising a cup-shaped metal member having a bottom portion provided with a central bore, and a side portion, th flow lines of the metal, as taken in a'plane through the longitudinal axis of the case having an end at the outside surface of the bottom portion and said line extending longitudinally of the side portion.

2. A cartridge case comprising a cup-shaped metal member having a bottom portion provided with a boss on its inner surface and with a central bore passing through said boss, and a side portion, the flow lines of the metal as taken in a plane through the longitudinal axis of the case having an S shape, said flow lines having an end at the outer surface of the bottom portion adjacent the bore, one curved portion in the boss near the bore, a second curved portion in the bottom portion between the boss and the side portion and said lines extending longitudinally of the side portion.

ADRIAAN JAN JURRIAAN LAMBEEK. 

